Specially designed for patients with heart conditions, the device will help to detect early signs of stroke and heart attacks.

Researchers from the engineering faculty of the Chinese University of Hong Kong (CUHK) have developed unobtrusive blood pressure (BP) sensor devices.

Specially designed for patients with heart conditions, these waterproof and thin devices can be worn as a wristband, or weaved into clothes, bedsheets or pillow cases.

When connected to a wireless network, the device can measure a patient's blood pressure accurately, and detect early signs of stroke and heart attacks. The sensors use optical, electronic and mechanical measurement techniques, to detect blood flow and monitor various health data through the colour reflected by the human skin and the depth of the images.

According to statistics from Hong Kong's Census and Statistics Department, more than half of people aged 65 or above suffered from hypertension in 2015, which puts them at higher risks of stroke and other cardiovascular diseases.

Automated and accurate BP devices, such as the new wearable sensor, can help prevent such diseases from occurring and alleviate pressure on carers.

The device provides continous real-time measurement of a user's BP and heart rate without disrupting a patient when he is asleep at night. This is useful, as most strokes and heart attacks are known for taking place at night, explained Prof. Zhao Ni, associate professor of the Department of Electronic Engineering at CUHK who co-led the research team. The other leader was Prof Zhang Yuan-ting, adjunct professor of the same department.

According to the researchers, the wearable BP sensor consumes only 3nW (nano Watt) of power. When the battery is running low, it can switch from optical to mechanical mode of detection, further reducing power consumption to ensure uninterrupted measurement and monitoring.

Prof. Zhao hopes that the sensors will help create a database of blood pressure records, along with other health records. She explained such a database could help medical researchers look into further cures for cardiovascular diseases.

Meanwhile, the team is planning to broaden the sensors' applications to monitor rate of breathing and oxygen levels, so that the finger pulse oximeter can be replaced.